IPhone N00blet

I have a few questions concerning the jailbreaking/unlocking/I'm a noob...

1. Is it possible to purchase an Iphone 3GS from Apple's website without buying a plan?
2. If in fact number 1 is possible what are the steps needed to be taken to use this newly purchased device through a different carrier such as t-mobile(jailbreaking/unlocking/etc.)?
3. Is it possible to buy a SIM card from a carrier such as t-mobile without buying a phone?
4. Is it possible to use an Iphone 3GS with a different SIM card?
5. What would be the best plan to get for an unlocked Iphone?

I think those questions sum up a complete scenario of noobishness.

-Thanks

PS(I have done some searching about these topics on the forums but would like a complete set of answers in one place)
PSS

I have a few questions concerning the jailbreaking/unlocking/I'm a noob...

1. Is it possible to purchase an Iphone 3GS from Apple's website without buying a plan?
2. If in fact number 1 is possible what are the steps needed to be taken to use this newly purchased device through a different carrier such as t-mobile(jailbreaking/unlocking/etc.)?
3. Is it possible to buy a SIM card from a carrier such as t-mobile without buying a phone?
4. Is it possible to use an Iphone 3GS with a different SIM card?
5. What would be the best plan to get for an unlocked Iphone?

I think those questions sum up a complete scenario of noobishness.

-Thanks

PS(I have done some searching about these topics on the forums but would like a complete set of answers in one place)
PSS